1. Technical Field
The present invention relates generally to automotive paint finishing processes and more particularly to an improved priming method.
2. Discussion
The paint finish on a new vehicle is often regarded as the single most noticeable visual feature of the vehicle. When the finish is smooth, even and attractive, persons viewing the vehicle are likely to be influenced as to the quality of the vehicle in a positive manner. Conversely, when the paint finish contains defects, persons viewing the vehicle are likely to attribute a lack of quality to the vehicle generally. Accordingly, vehicle manufacturers and paint suppliers have expended vast resources to produce enhanced paint application processes to improve the quality and durability of the finish of the vehicle and eliminate defects associated with the application of paint to the vehicle.
Despite these efforts, significant improvements relating to process of vehicle priming have not been made. Typical prior art priming methods have included a first coat of paint that is applied through electrodeposition in which a cathodic or anodic type primer (e-coat primer) is applied to the body of the vehicle. As these electrodeposited primers are susceptible to degradation by ultraviolet light, their use increased the risk of a delamination. More specifically, extended exposure to ultraviolet light would penetrate the e-coat primer, causing it to delaminate from the vehicle body. Since each subsequent coat of paint on the vehicle body is essentially bonded to the previous coat of paint, the delamination of the primer from the vehicle body creates a catastrophic failure in the vehicle finish wherein the entire finish is lost over the area of the failure.
To reduce the risk of delamination failures, a second primer coat, traditionally a solvent or water-based paint which is resistant to ultraviolet light, has been sprayed over the first primer coat. In recent years, powder primers were developed to replace the liquid paints due to environmental considerations and also because powder paints are stronger and more durable, thus providing improved chip resistance. Despite the apparent success of liquid and powder paints for a second primer coat, their use is attendant with several significant drawbacks.
While both liquid and powder paints can be applied with automatic equipment, it is frequently necessary to include one or more manual "touch-up" stations which are operated with production personnel. Frequently, these manual stations operate at low utilization and the quality of the finish is highly dependent on the skill of the personnel operating the station. Both types of paint also include costly capital equipment for applying the paint as well as controlling the environment in which the paint is applied to the vehicle body.
Another significant drawback concerns the robustness of the processes for applying these paints. A myriad of factors contributes to the overall quality of the finish of vehicle bodies painted with either powder or liquid paint. Small deviations in temperature, humidity, airflow, paint viscosity, etc. can have significant effects on the quality of the finish. As such, the use of these types of paint requires the continuous monitoring and control of a multitude of process variables. Naturally, the cost to continually monitor and control the process variables is considerable.
Therefore, there remains a need in the art for an improved priming method which provides a more robust priming process which can be entirely automated and which does not require additional equipment to apply powder or solvent or water based liquid paints.